Argillic Horizons in Stratified Drift: Luverne End Moraine, Eastern North Dakota

horizons on a precision farming research site in Barnes County, North Dakota for precisely these reasons. An Although pedogenesis and landscape evolution have occurred on intriguing aspect of this work concerns the fact that soils the eastern North Dakota till plain since the inception of the Holocene, soils with argillic horizon are recognized on a very limited basis. with argillic horizons have not been mapped on any Argillic soils are not mapped in well-drained positions on the youngest moraine landscapes in central or eastern North Dakota drift prairie landscapes. Roughly half of 47 pedons examined at a north of Sargent County, which borders South Dakota. precision farming research site in Barnes County, North Dakota show The Forman series (Fine-loamy, mixed, superactive, evidence of genetic argillic horizons based on soil structure, hand frigid Calcic Argiudolls), which is mapped in northeasttexturing, and cutan presence. This study applies physical and microern South Dakota and Sargent County, North Dakota, morphological evidence to verify that diagnostic argillic horizons have is thought to form on older till than that in Barnes formed in well-drained settings on this eastern North Dakota landCounty (Aandahl 1982). scape. Total clay distributions and fine/total clay ratios show marked A large number of moraines are distributed throughincreases in genetic argillic horizons compared with surface horizons out central and eastern North Dakota and individual and parent materials. The argillic horizons average about 28 cm in thickness; only two pedons were thinner than 7.5 cm. Consequently, moraines frequently extend across several counties. Lithe increase in total clay and fine clay distributions, and the thickness thology and sediment sizes encountered on the numercriteria required to meet diagnostic horizon status as established by ous moraines are similar (Clayton et al., 1980). Soil map Soil Taxonomy are satisfied. The upper argillic horizon boundary of units recognized on the moraines commonly form in till, seven profiles was 50 cm or more below the surface, possibly indicating water-worked till, sandy sediments, or sediments with relict argillic horizons. Micromorphologic evidence shows the presa sandy or coarse-loamy mantle above till. Soil parent ence of illuvial clay in the three soils sampled for microscopy. Porosity materials on the moraines and the lower elevation drift variations caused by the argillic horizons likely affect subsurface flow prairie have both been exposed to surficial weathering and may be responsible for variable N levels measured for these soils. and similar vegetation for similar amounts of time, yet These soils formed in well-drained landscape settings, where stratified soils with argillic horizons have been recognized on a drift may predispose the soils to illuviation. very limited basis, and only on the drift prairie. The physical and morphological properties of drift prairie soils were a major focus of extensive field reG Smith (1986) stated that argillic horizons were search by North Dakota Agricultural Experiment Stanot “weighted more heavily” in Soil Taxonomy tion personnel in the late 1950s and early 1960s (McClelthan other diagnostic subsurface horizons. However, the land et al., 1959; Mogen et al., 1959). The typical B definition, recognition, and genesis of horizons featuring horizon in well-drained positions was described as a accumulated silicate clays have occasionally dominated “color B” with high chroma, but a “texture B” having pedological discourse. Smith (1986) believed the argillic clay films on ped faces that “range from thin and patchy horizon was important not so much for what it was, but to thin and continuous” was noted as well (McClelland for what it does: increase nutrient status, enhance water et al., 1959, p. 53). Subsequently, Redmond and Omodt retention, reduce permeability and “perch” water, as (1967) suggested that the Barnes soil series, an extensive well as reflect geomorphic stability of the landscape. soil of the drift prairie, acquired three developmental These interpretations, crucial to understanding water forms in eastern North Dakota due to different expresand solute movement at the landscape scale, explain sions of the B horizon. why soil stratigraphy has taken on new meaning for Clearly, illuvial processes were recognized by these environmental and hydrogeological assessments. Many early researchers, but Aandahl (1982, p. 10) stated that recent studies have attempted to quantify the role argilargillic horizons did not form in the Udic Borolls (curlic horizons, and other restrictive subsurface horizons, rently Hapludolls) because the soils were immature and exert in soil water flow (McDaniel and Falen, 1994; “formed in recent glacial till.” Soils with argillic horizons Perillo et al., 1999; Shaw et al., 2001). We have been were “those formed under the influence of trees of the investigating the occurrence and distribution of argillic Turtle Mountains, those in shallow depressions with greater leaching by extra water, but shallow enough to Dep. of Soil Science, 106 Walster Hall, North Dakota State Univ., permit frequent wetting and drying, and those in older Fargo, ND 58105. Received 1 Aug. 2002. *Corresponding author ([email protected]). tills; some formed in glacial till are clayey where influenced by sodium” (Aandahl, 1982, p. 10). These enviPublished in Soil Sci. Soc. Am. J. 67:1790–1796 (2003). ronmental settings, and the multiple processes required  Soil Science Society of America 677 S. Segoe Rd., Madison, WI 53711 USA to form diagnostic argillic horizons in North Dakota